Vehicle hydraulic device

ABSTRACT

A check valve provided makes it possible to operate a vane pump smoothly even at the start of the vane pump by maintaining an oil pressure in backpressure oil passages inside the vane pump while the vane pump is stopped. The check valve opens at the point in time when an oil pressure control device, to which a working fluid is supplied from the vane pump, has been filled with the working fluid and the oil pressure in discharge oil passages communicating with the oil pressure control device has risen and exceeded the oil pressure in the backpressure oil passages. Thus, the check valve is prevented from opening and closing repeatedly, so that the durability of the check valve is improved.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to Japanese Patent Application No. 2015-181241 filed on Sep. 14, 2015, the entire contents of which are hereby incorporated by reference.

BACKGROUND

1. Technical Field

The present disclosure relates to a vehicle hydraulic device having a vane pump as the oil pressure source, and more particularly to a technique for enhancing the durability of a valve that applies a backpressure to vanes.

2. Description of Related Art

A vane pump driven by an engine has, inside a pump housing with a substantially elliptical inner peripheral cam surface, for example, a plurality of variable-displacement pump chambers that are defined by a rotor fitted on a rotating shaft and a plurality of vanes radially fitted into vane housing groves formed in the rotor. As the vanes rotate while being pressed against the inner peripheral surface of the pump housing, the volumes of the pump chambers vary and a discharge force is applied to a working fluid.

The force for pressing the vanes against the inner peripheral surface of the pump housing is derived from a rotational centrifugal force and a backpressure that presses the vanes against the inner peripheral surface of the pump housing inside the rotor, and the working fluid discharged from the vane pump is used to obtain this backpressure. However, if the rotation speed of the rotor is low at the start of the vane pump, even when the centrifugal force of the rotating vanes and the backpressure generated by the working fluid discharged from the vane pump are combined, the force that presses the vanes against the inner peripheral surface of the pump housing may be too small for the pump to start smoothly.

To address this problem, Japanese Patent Application Publication No. 10-196557 discloses a technique for preventing the backpressure inside a vane pump from decreasing while the vane pump is stopped. Specifically, in this vane pump, vane housing grooves provided inside the rotor and a discharge oil passage that supplies a working fluid discharged from the vane pump to an oil pressure control device communicate with each other through a backpressure oil passage. A check valve that opens only when the pressure on the vane pump side is equal to or higher than a predetermined value is provided on the downstream side from the communication point, i.e., on the side of an oil pressure control circuit that receives and consumes a supply of oil pressure from the vane pump. Thus, the proposed vane pump operates smoothly even at the start.

In the vane pump of JP 10-196557 A, when the pressure of the working fluid discharged from the vane pump to the valve becomes equal to or higher than the predetermined value, the check valve provided in the discharge oil passage extending from the vane pump to the oil pressure control circuit shifts from a closed state to an open state. However, the check valve is closed again when the oil pressure is lowered by the opening of the valve. Thus, the durability of the check valve may decline as the check valve opens and closes repeatedly.

SUMMARY

Having been devised in the context of the above situation, the present disclosure provides a vehicle hydraulic device including a vane pump, in which a check valve is provided to allow the vane pump to operate smoothly even at the start and the durability of the check valve is improved.

According to one aspect of the present disclosure, a vehicle hydraulic device including a vane pump, an oil pressure control circuit and a check valve is provided. The vane pump is driven to rotate by an engine. The vane pump includes a pump housing, a plurality of vanes, and a rotor. The pump housing has an inner peripheral cam surface with an elliptical sectional shape. The plurality of vanes are provided inside the pump housing. The rotor provides vane housing grooves that house the plurality of vanes so as to be movable in a radial direction of the rotor. The oil pressure control circuit has a backpressure oil passage and a discharge oil passage. The backpressure oil passage is configured to supply a backpressure to the plurality of vanes inside the vane housing grooves. The discharge oil passage is configured to: (i) introduce a working fluid discharged from the vane pump, and (ii) supply the working fluid to a device other than the vehicle hydraulic device. The check valve is provided between the backpressure oil passage and the discharge oil passage. The check valve is configured to: (i) open when the oil pressure of the working fluid in the discharge oil passage discharged from the vane pump is higher than the oil pressure in the backpressure oil passage, and (ii) block the flow of the working fluid when the oil pressure of the working fluid in the discharge oil passage discharged from the vane pump is equal to or lower than the oil pressure in the backpressure oil passage.

According to another aspect of the present disclosure, a vehicle hydraulic device including a vane pump and an oil pressure control circuit is provided. The vane pump is driven to rotate by an engine. The vane pump includes a pump housing, a plurality of vanes, a rotor, and a check valve. The pump housing has an inner peripheral cam surface with an elliptical sectional shape. The plurality of vanes are provided inside the pump housing. The rotor provides vane housing grooves that house the plurality of vanes so as to be movable in a radial direction of the rotor. The check valve is configured to open to allow the flow of a working fluid and close to shut off the flow of the working fluid. The oil pressure control circuit has a backpressure oil passage, a discharge oil passage, and a check valve. The backpressure oil passage is configured to supply a backpressure to the plurality of vanes inside the vane housing grooves. The discharge oil passage is configured to introduce the working fluid discharged from the vane pump and supply the working fluid to a device other than the vehicle hydraulic device through the discharge oil passage. The check valve is interposed between the backpressure oil passage and the discharge oil passage. The check valve is configured to: (i) open when the oil pressure of the working fluid in the discharge oil passage discharged from the vane pump is higher than the oil pressure in the backpressure oil passage, and (ii) block the flow of the working fluid when the oil pressure of the working fluid in the discharge oil passage discharged from the vane pump is equal to or lower than the oil pressure in the backpressure oil passage.

If such a configuration is adopted, the check valve opens at the point in time when the oil pressure control circuit, to which the working fluid is supplied from the vane pump, has been filled with the working fluid and the oil pressure in the discharge oil passage communicating with the oil pressure control circuit has risen and exceeded the oil pressure in the backpressure oil passage. Thus, the check valve is prevented from opening and closing repeatedly, so that the durability of the check valve is improved.

SUMMARY

Having been devised in the context of the above situation, the present disclosure provides a vehicle hydraulic device including a vane pump, in which a check valve is provided to allow the vane pump to operate smoothly even at the start and the durability of the check valve is improved.

According to one aspect of the present disclosure, a vehicle hydraulic device including a vane pump and an oil pressure control circuit, the vehicle hydraulic device further including a check valve, is provided. The vane pump is driven to rotate by an engine. The vane pump includes a pump housing, a plurality of vanes, and a rotor. The pump housing has an inner peripheral cam surface with an elliptical sectional shape. The plurality of vanes are provided inside the pump housing. The rotor provides vane housing grooves that house the plurality of vanes so as to be movable in a radial direction of the rotor. The oil pressure control circuit has a backpressure oil passage and a discharge oil passage. The backpressure oil passage is configured to supply a backpressure to the plurality of vanes inside the vane housing grooves. The discharge oil passage is configured to: (i) introduce a working fluid discharged from the vane pump, and (ii) supply the working fluid to a device other than the vehicle hydraulic device. The check valve is provided between the backpressure oil passage and the discharge oil passage. The check valve is configured to: (i) open when the oil pressure of the working fluid in the discharge oil passage discharged from the vane pump is higher than the oil pressure in the backpressure oil passage, and (ii) block the flow of the working fluid when the oil pressure of the working fluid in the discharge oil passage discharged from the vane pump is equal to or lower than the oil pressure in the backpressure oil passage.

According to another aspect of the present disclosure, a vehicle hydraulic device including a vane pump and an oil pressure control circuit is provided. The vane pump is driven to rotate by an engine. The vane pump includes a pump housing, a plurality of vanes, a rotor, and a check valve. The pump housing has an inner peripheral cam surface with an elliptical sectional shape. The plurality of vanes are provided inside the pump housing. The rotor provides vane housing grooves that house the plurality of vanes so as to be movable in a radial direction of the rotor. The check valve is configured to open to allow the flow of a working fluid and close to shut off the flow of the working fluid. The oil pressure control circuit has a backpressure oil passage, a discharge oil passage, and a check valve. The backpressure oil passage is configured to supply a backpressure to the plurality of vanes inside the vane housing grooves. The discharge oil passage is configured to: (i) introduce the working fluid discharged from the vane pump, and (ii) supply the working fluid to a device other than the vehicle hydraulic device through the discharge oil passage. The check valve is interposed between the backpressure oil passage and the discharge oil passage. The check valve is configured to: (i) open when the oil pressure of the working fluid in the discharge oil passage discharged from the vane pump is higher than the oil pressure in the backpressure oil passage, and (ii) block the flow of the working fluid when the oil pressure of the working fluid in the discharge oil passage discharged from the vane pump is equal to or lower than the oil pressure in the backpressure oil passage.

If such a configuration is adopted, the check valve opens at the point in time when the oil pressure control circuit, to which the working fluid is supplied from the vane pump, has been filled with the working fluid and the oil pressure in the discharge oil passage communicating with the oil pressure control circuit has risen and exceeded the oil pressure in the backpressure oil passage. Thus, the check valve is prevented from opening and closing repeatedly, so that the durability of the check valve is improved.

BRIEF DESCRIPTION OF THE DRAWINGS

Features, advantages, and technical and industrial significance of exemplary embodiments will be described below with reference to the accompanying drawings, in which like numerals denote like elements, and wherein:

FIG. 1 is a schematic view illustrating the configuration of the major part of a vehicle hydraulic device of a first embodiment;

FIG. 2 is a front view of a vane pump of the vehicle hydraulic device of FIG. 1, with a cover thereof removed;

FIG. 3 is a sectional view of the major part inside a recess of a vane pump of a second embodiment;

FIG. 4 is a front view of a cover of FIG. 3;

FIG. 5 is a front view of a first side plate of FIG. 3;

FIG. 6 is a rear view of the first side plate of FIG. 3;

FIG. 7 is a front view of a second side plate of FIG. 3;

FIG. 8 is a rear view of the second side plate of FIG. 3;

FIG. 9 is a rear view of a third side plate of FIG. 3;

FIG. 10 is a front view of a body of FIG. 3;

FIG. 11 is a sectional view of the major part of the second embodiment showing the second side plate, in which a first check valve is incorporated, the third side plate, and the body;

FIG. 12A is a front view of a retainer, constituting a part of the first check valve of FIG. 11, as seen from the side of the body;

FIG. 12B is a front view of a leaf spring, constituting a part of the first check valve of FIG. 11, as seen from the side of the body; and

FIG. 12C is a front view of a sheet, constituting a part of the first check valve of FIG. 11, as seen from the side of the body.

DETAILED DESCRIPTION OF EMBODIMENTS

In the following, a first embodiment of a vehicle hydraulic device will be described in detail with reference to the drawings.

FIG. 1 is a schematic view illustrating the configuration of the vehicle hydraulic device. A vehicle hydraulic device 10 includes a check valve 90, and a vane pump 14 that supplies a working fluid to an oil pressure control device 12 functioning as an oil pressure control circuit that consumes the working fluid, such as the hydraulic cylinder of the sheave etc. of an automatic transmission (A/T) or a continuously variable transmission (CVT).

The vane pump 14 is driven by the rotation of an engine 15. The vane pump 14 has a first suction port 22 and a second suction port 24 through which the working fluid stored in an oil pan 18 is suctioned via an oil strainer 20, and a first discharge port 26 and a second discharge port 28 through which the suctioned working fluid is discharged to the outside of the pump. The vane pump 14 further has a first backpressure groove 62 and a second backpressure groove 64 that supply a backpressure to a plurality of vanes 81 that suction and discharge the working fluid. The working fluid is sent from the suction ports 22, 24 to the discharge ports 26, 28 through pump chambers P formed by the vanes 81.

A first discharge oil passage 30 and a second discharge oil passage 31, each functioning as the discharge oil passage, are connected to the first discharge port 26 and the second discharge port 28, respectively. The first discharge oil passage 30 and the second discharge oil passage 31 are further connected to a discharge oil passage 29, and serve as working fluid supply passages to the oil pressure control device 12 through which the working fluid discharged from the first discharge port 26 and the second discharge port 28 is pumped to the oil pressure control device 12.

A first backpressure oil passage 35 and a second backpressure oil passage 36, each corresponding to the backpressure oil passage, are connected to the first backpressure groove 62 and the second backpressure groove 64, respectively. A check valve 90 is provided between the first and second discharge oil passages 30, 31 and the first and second backpressure oil passages 35, 36.

A suction oil passage 34 connects the first and second suction ports 22, 24 of the vane pump 14 and the oil pan 18 to each other via the oil strainer 20 such that the working fluid stored in the oil pan 18 is suctioned into the first suction port 22 and the second suction port 24. A return oil passage 32 returns the working fluid of the oil pressure control device 12 to the suction oil passage 34 of the vane pump 14.

FIG. 2 is a front view showing the vane pump 14 of the vehicle hydraulic device 10 with a pump cover removed. The vane pump 14 is composed of: a body 44 having a substantially columnar recess 16 formed therein; a substantially cylindrical cam ring 70, corresponding to a pump housing, that is fitted inside the recess 16 so as to be unable to rotate relative to the body 44; a disc-shaped side plate 37 that is mounted so as to be interposed between a bottom wall surface of the recess 16 of the body 44 and the cam ring 70, with one flat surface and the other flat surface of the side plate 37 respectively in contact with the bottom wall surface of the recess 16 and a substantially circular one end surface of the cam ring 70; a columnar rotor 74 housed such that the outer peripheral surface faces an inner peripheral cam surface 78 of the cam ring 70 with a small space therebetween, and that one end surface in the direction of a rotational axis can come into sliding contact with the other flat surface of the side plate 37; a pump shaft 76 that is fixed to the rotor 74 coaxially with the rotational axis of the rotor 74 and rotatably supported on the body 44, and rotates the rotor 74 in the direction of the arrow indicated in FIG. 2, i.e., in the clockwise direction, according to the driving of a driving source, such as the engine 15; and the pump cover (not shown) that is fastened to the body 44 so as to be in contact with the substantially circular other end surface of the cam ring 70 and cover the opening of the recess 16 while being able to come into sliding contact with the other end surface of the rotor 74 in the axial direction.

The cam ring 70 has the inner peripheral cam surface 78 that is the inner peripheral surface with a substantially elliptical sectional shape. The rotor 74 includes a plurality of slits 80, corresponding to the vane housing grooves, that are formed over the entire axial length of the outer peripheral surface, radially from a center part in the radial direction toward the outer peripheral surface at regular intervals in the circumferential direction, and the plurality of rectangular, plate-shaped vanes 81 that are fitted into the slits 80. Since the slits 80 house the vanes, the slits 80 are also called vane housing grooves. The vane 81 is inserted into the slit 80 such that the side surfaces of the vane 81 in the circumferential direction of the rotor 74 can slide in the radial direction of the rotor 74 over an inner wall of the slit 80 facing the vane 81; that the side surfaces in the axial direction come into sliding contact with the other end surface of the side plate 37 and an inner wall surface of the pump cover, respectively; and that the radially outer end surface of the vane 81 can slide over the inner peripheral cam surface 78 of the cam ring 70.

When the rotor 74 is driven to rotate, the vane 81 is pushed out toward the radially outer side of the rotor 74 from the inner wall of the slit 80 under the backpressure from the first backpressure groove 62 and the second backpressure groove 64, so that the radially outer end surface of the vane 81 is pressed against the inner peripheral cam surface 78 of the cam ring 70 and, in this state, slides over the inner peripheral cam surface 78 in the rotation direction of the rotor 74. Thus, the plurality of pump chambers P are defined by the side surfaces of the adjacent vanes 81 facing each other in the circumferential direction, the inner peripheral cam surface 78, the outer peripheral surface of the rotor 74, the other end surface of the side plate 37, and the inner wall surface of the pump cover. Since the inner peripheral cam surface 78 has a substantially elliptical shape, as the rotor 74 makes one rotation, the vane 81 reciprocates twice inside the slit 80 in the radial direction of the rotor 74, so that the volume of the pump chamber P increases and decreases twice.

In the side plate 37 and the body 44, the pair of first suction port 22 and second suction port 24 communicating with the pump chambers P, which increase in volume according to the rotation of the rotor 74, are formed across the pump shaft 76 so as to straddle both the side plate 37 and the body 44. In the side plate 37 and the body 44, the pair of first discharge port 26 and second discharge port 28 communicating with the pump chambers P, which decrease in volume according to the rotation of the rotor 74, are formed across the pump shaft 76 so as to straddle both the side plate 37 and the body 44. The first discharge port 26 is located on the front side in the rotation direction of the rotor 74 relative to the first suction port 22. The second discharge port 28 is located on the front side in the rotation direction of the rotor 74 relative to the second suction port 24. It is also possible to form the ports 22, 24, 26, 28 only in the side plate 37, instead of forming these ports so as to straddle both the side plate 37 and the body 44.

The side plate 37 communicates with the inner peripheral ends of the slits 80, into which the vanes 81 defining the pump chambers P are fitted, between the first suction port 22 and the first discharge port 26. The first backpressure groove 62 and the second backpressure groove 64 that supply a backpressure for pressing the vanes 81 against the inner peripheral cam surface 78 are formed in a semi-annular shape in the circumferential direction of the side plate 37. The first backpressure groove 62 and the second backpressure groove 64 communicate with the first backpressure oil passage 35 and the second backpressure oil passage 36, respectively.

When the vane pump 14 is started according to the driving of the engine 15 and the rotor 74 is rotated in the clockwise direction in FIG. 2, the working fluid inside the oil pan 18 is suctioned through the suction oil passage 34 into the first suction port 22 and the second suction port 24, and carried to each pump chamber P of the vane pump 14 of which the volume increases gradually as the rotor 74 rotates. As the rotor 74 rotates and the volumes of the pump chambers P decrease accordingly, the working fluid suctioned into the pump chambers P is discharged through the first discharge port 26 and the second discharge port 28 to the first discharge oil passage 30 and the second discharge oil passage 31, respectively. The oil pressure in the first backpressure oil passage 35 and the second backpressure oil passage 36 is supplied as a backpressure for pressing the radially outer end surfaces of the vanes 81 defining the pump chambers P against the inner peripheral cam surface 78 of the cam ring 70.

The check valve 90 is provided in the oil passage that connects the first and second backpressure oil passages 35, 36 and the first and second discharge oil passages 30, 31 to each other. The check valve 90 opens when the oil pressure of the working fluid in the discharge oil passages 30, 31 discharged from the vane pump 14 is higher than the oil pressure in the backpressure oil passages 35, 36, and the check valve 90 closes and blocks the flow of the working fluid when the oil pressure of the working fluid in the discharge oil passages 30, 31 discharged from the vane pump 14 is equal to or lower than the oil pressure in the backpressure oil passages 35, 36. In this way, the backpressure for pressing the radially outer end surfaces of the vanes 81 defining the pump chambers P of the vane pump 14 against the inner peripheral cam surface 78 of the cam ring 70 is maintained.

Thus, the check valve 90 is provided in the vehicle hydraulic device 10 of the first embodiment, which makes it possible to operate the vane pump 14 smoothly even at the start of the vane pump 14 by maintaining the oil pressure in the backpressure oil passages 35, 36 connected to the vane pump while the vane pump 14 is stopped. The check valve 90 opens when the oil pressure of the working fluid in the discharge oil passages 30, 31 discharged from the vane pump 14 is higher than the oil pressure in the backpressure oil passages 35, 36, and the check valve 90 closes and shuts off the flow of the working fluid when the oil pressure of the working fluid in the discharge oil passages 30, 31 discharged from the vane pump is equal to or lower than the oil pressure in the backpressure oil passages 35, 36. With such a check valve 90 provided between the backpressure oil passages 35, 36 and the discharge oil passages 30, 31, the oil pressure control device 12, to which the working fluid is supplied from the vane pump 14, is filled with the working fluid. Then, the check valve 90 opens at the point in time when the oil pressure in the discharge oil passages 30, 31 communicating with the oil pressure control device 12 has risen and exceeded the oil pressure in the backpressure oil passages. Thus, the check valve 90 is prevented from opening and closing repeatedly, so that the durability of the check valve 90 is improved.

Moreover, in the first embodiment, the check valve 90 is provided in the backpressure oil passages 35, 36 to which the working fluid is supplied at a lower flow rate, so that especially the torque loss of the vane pump 14 can be reduced during high-speed rotation of the vane pump 14 compared with when the check valve 90 is provided in the discharge oil passage 29 to which the working fluid is supplied at a higher flow rate.

Next, a second embodiment will be described. In the following second embodiment, those parts that have substantially the same functions as in the first embodiment will be denoted by the same reference signs and the detailed description thereof will be omitted. The vehicle hydraulic device 10 of the second embodiment is different from that of the first embodiment in that the check valve 90 is built inside a second side plate 40, and that a plurality of side plates, a first side plate 38, the second side plate 40, and a third side plate 42 having oil passages accompanying the check valve, are used. Therefore, only such differences in configuration will be described in detail using FIG. 3 to FIG. 11.

FIG. 3 is a sectional view of the vane pump 14. The body 44 is provided with a first discharge opening 54 and a second discharge opening 56 communicating with the inside of the recess 16. The third side plate 42 and the second side plate 40 are fitted inside the recess 16 of the body 44 so as to be unable to rotate relative to the body 44. The cam ring 70 is fitted so as to be unable to rotate relative to the body 44, and the rotor 74 radially housing the plurality of vanes 81 inside is installed inside the recess 16 of the body 44. The first side plate 38 is fitted inside the recess 16 of the body 44 so as to be unable to rotate relative to the body 44. A cover 72 is mounted so as to cover the opening of the recess 16 of the body 44, and the cover 72 is provided with a first suction opening 46, a second suction opening 48, and a pump shaft insert hole 77 through which the pump shaft 76 is passed.

The description of the structures and functions of the plurality of vanes 81 and the rotor 74 housed inside the cam ring 70, which are the same as described in the first embodiment, will be omitted. The oil passages inside the vane pump 14, and a first check valve 98 and a second check valve 99, each functioning as the check valve, will be described in the order from the suction to discharge of the working fluid, i.e., in the order of the cover 72, the first side plate 38, the second side plate 40, the third side plate 42, and the body 44.

FIG. 4 is a front view of the cover 72. The cover is provided with the first suction opening 46 and the second suction opening 48 connected to the suction oil passage 34, and the pump shaft insert hole 77 at the center of the cover. Since the pump shaft insert hole 77 is also provided in each of the first side plate 38, the second side plate 40, the third side plate 42, and the body 44, the description of the pump shaft insert hole 77 will be omitted from the subsequent description. FIG. 5 is a front view of the first side plate 38 as seen from the side of the cover 72. The first side plate 38 has a first suction opening 46 a connected to the first suction opening 46 and a second suction opening 48 a connected to the second suction opening 48.

Since the working fluid is sent to the pump chambers P through the first suction opening 46 of the cover 72 of FIG. 4 and the first suction opening 46 a of the first side plate 38, these openings correspond to the first suction port 22 of the first embodiment. Since the working fluid is sent to the pump chambers P through the second suction opening 48 of the cover 72 and the second suction opening 48 a of the first side plate 38, these openings correspond to the second suction port 24 of the first embodiment.

FIG. 6 is a rear view of the first side plate 38. On the rear side of the first side plate 38, a first backpressure groove 63 a and a second backpressure groove 65 a, each functioning as the backpressure oil passage, are formed in a semi-annular shape in the circumferential direction around the pump shaft insert hole 77. The first backpressure groove 63 a and the second backpressure groove 65 a supply a backpressure to be applied to the vanes 81.

FIG. 7 is a front view of the second side plate 40 as seen from the side of the cover 72. The second side plate 40 has a first backpressure groove 63 b and a second backpressure groove 65 b, each functioning as the backpressure oil passage, formed as semi-annular grooves in the circumferential direction around the pump shaft insert hole 77. The backpressure grooves 63 b, 65 b supply a backpressure to be applied to the vanes 81. The openings of the first backpressure groove 63 b and a first bypass passage 82 b of FIG. 8 functioning as the backpressure oil passage partially overlap and communicate with each other, while the openings of the second backpressure groove 65 b and a second bypass passage 84 b of FIG. 8 functioning as the backpressure oil passage partially overlap and communicate with each other. The first discharge groove 50 b is open in the same shape and at the same position as a first discharge groove 50 c of the third side plate 42 of FIG. 9, and communicates with the first discharge opening 54 of the body, while the second discharge groove 52 b is open in the same shape and at the same position as a second discharge groove 52 c of the third side plate 42 of FIG. 9, and communicates with the second discharge opening 56 of the body. Since the first discharge grooves and the second discharge grooves carry the working fluid from the pump chambers P, these grooves correspond to the first discharge port 26 and the second discharge port 28 of the first embodiment. A first suction groove 58 and a second suction groove 60 are formed at positions corresponding to the first suction opening 46 a and the second suction opening 48 a that are provided in the first side plate 38 across the rotor 74, and since the first suction groove 58 and the second suction groove 60 have a wide opening, the amount of working fluid required for the pump chambers P defined by the vanes 81 is supplied.

FIG. 8 is a rear view of the second side plate 40. On the rear side of the second side plate 40, the first discharge groove 50 b and the second discharge groove 52 b are fully open, and the first bypass passage 82 b holding the first check valve 98 and the second bypass passage 84 b holding the second check valve 99 are provided. As the first bypass passage 82 b and the second bypass passage 84 b of FIG. 8 are partially open, these bypass passages partially communicate with the first backpressure groove 63 b and the second backpressure groove 65 b, respectively.

FIG. 9 is a rear view of the third side plate 42. On the rear side of the third side plate 42, the first discharge groove 50 c and the second discharge groove 52 c are fully open, and a first bypass passage 82 c and a second bypass passage 84 c are formed. The first bypass passage 82 c and the second bypass passage 84 c are each formed of two semi-circular through-grooves.

FIG. 10 is a front view of the body. With the circular recess 16 open at the end formed in an outer center part of the body 44, the body 44 has a one-end-closed cylindrical shape. The first discharge opening 54 connected to the first discharge oil passage 30 is formed so as to penetrate the bottom wall of the body 44. Similarly, the second discharge opening 56 connected to the second discharge oil passage 31 is formed so as to penetrate the bottom wall of the body 44. The bottom wall further has a first bypass groove 86 formed of an annular groove formed at a position corresponding to the first bypass passage 82 b of the second side plate 40 and a groove providing communication between that annular groove and the first discharge opening 54. Moreover, the bottom wall has a second bypass groove 88 formed of an annular groove formed at a position corresponding to the second bypass passage 84 b of the second side plate 40 and a groove providing communication between that annular groove and the second discharge opening 56.

FIG. 11 is a sectional view of the major part showing the second side plate 40, in which one of the first check valve 98 and the second check valve 99 is incorporated, the third side plate 42, and the body 44. The first check valve 98 and the second check valve 99 are held respectively inside the first bypass passage 82 b and the second bypass passage 84 b of the second side plate 40, and similarly composed of three members, a retainer 92, a leaf spring 94, and a sheet 96. In the following, the first check valve 98 will be described as a representative while the description of the second check valve 99 will be omitted.

FIGS. 12A, 12B, 12C are front views of the retainer 92, the leaf spring 94, and the sheet 96, constituting the first check valve 98, as seen from the side of the body 44. The retainer 92 and the leaf spring 94 have a ring shape. The sheet 96 has a disc shape with a circular opening at the center. The retainer 92 holds the leaf spring 94 inside the first bypass passage 82 b and the second bypass passage 84 b. The leaf spring 94 applies a force for pressing the sheet 96 against a columnar part provided at the center of the bypass passage 82 c of the third side plate 42. Under the force of the leaf spring 94, the circular opening at the center of the sheet 96 comes into contact with the surface of the third side plate 42, so that the opening of the sheet 96 is closed and the flow of the working fluid is blocked. Thus, the sheet 96 constituting a part of the first check valve 98 has one side surface in contact with the working fluid on the discharge opening side and the other side surface in contact with the working fluid on the backpressure groove side. Accordingly, the oil passage opens when the oil pressure of the working fluid at the first discharge opening 54 discharged from the vane pump 14 is higher than the oil pressure in the backpressure grooves of the rotor 74, the first side plate 38 and the second side plate 40, and the oil passage closes and the flow of the working fluid is blocked when the oil pressure is equal to or lower than the oil pressure in the backpressure grooves. In this way, the backpressure for pressing the radially outer end surfaces of the vanes 81 defining the pump chambers P of the vane pump 14 against the inner peripheral cam surface 78 of the cam ring 70 is maintained. Although the members constituting the first check valve 98 have been described as having a circular shape in a front view in the second embodiment, these members do not particularly have to be circular and may instead have a square shape or a polygonal shape, for example.

Thus, the vehicle hydraulic device 10 of the second embodiment is provided with the first check valve 98 and the second check valve 99, which makes it possible to operate the vane pump 14 smoothly even at the start of the vane pump 14 by maintaining the oil pressure in the first backpressure groove 62 and the second backpressure groove 64 inside the rotor 74 of the vane pump while the vane pump 14 is stopped.

The first check valve 98 and the second check valve 99 open at the point in time when the oil pressure control device 12, to which the working fluid is supplied from the vane pump 14 by the first check valve 98 and the second check valve 99, has been filled with the working fluid and the oil pressure in the discharge oil passages 30, 31 communicating with the oil pressure control device 12 has risen and exceeded the oil pressure in the backpressure oil passages 35, 36. Thus, the first check valve 98 and the second check valve 99 are prevented from opening and closing repeatedly, so that the durability of the first check valve 98 and the second check valve 99 is improved.

Moreover, when the first check valve 98 and the second check valve 99 are provided in the first bypass passage 82 b and the second bypass passage 84 b to which the working fluid is supplied at a lower flow rate, especially the torque loss of the vane pump 14 during high-speed rotation of the vane pump 14 can be reduced compared with when the check valve 90 is provided in the discharge oil passage 29 to which the working fluid is supplied at a higher flow rate.

While the present embodiments have been described above in detail with reference to the drawings, the present disclosure can also be implemented in other embodiments, and various modifications can be added within the scope of the disclosure.

For example, in the vane pump 14 of the first embodiment and the second embodiment, the cam ring 70 having the inner peripheral cam surface 78 is fitted in the recess 16 of the body 44. However, the present embodiments are not limited thereto, and, for example, the cam ring may be omitted by forming the inner peripheral cam surface 78, facing the outer peripheral surface of the rotor 74, directly on the inner peripheral surface of the recess 16 of the body 44.

Although the vane pump of the second embodiment is provided with the two check valves 98, 99, the present embodiments are not limited thereto and the number of the check valves may be one or more than two.

The vane pump of the second embodiment has been described with three types of side plates, but the present embodiment is not limited thereto. For example, it is also possible to omit the first side plate by machining the backpressure grooves 63 a, 65 a of the first side plate in the cover 72, or to omit the third side plate 42 and reduce the number of the side plates by machining the bypass grooves inside the body, instead of on the surface of the body as in the above embodiment. Alternatively, the number of the side plates may be increased to make the machining of the oil passage easier. 

What is claimed is:
 1. A vehicle hydraulic device comprising: a vane pump that is driven to rotate by an engine, the vane pump including a pump housing, a plurality of vanes, and a rotor, the pump housing having an inner peripheral cam surface with an elliptical sectional shape, the plurality of vanes being provided inside the pump housing, the rotor providing vane housing grooves that house the plurality of vanes so as to be movable in a radial direction of the rotor; and an oil pressure control circuit including backpressure oil passages and discharge oil passages, the backpressure oil passages being configured to supply a backpressure to the plurality of vanes inside the vane housing grooves, the discharge oil passages being configured to: (i) introduce a working fluid discharged from the vane pump, and (ii) supply the working fluid to a device other than the vehicle hydraulic device, a check valve provided between the backpressure oil passages and the discharge oil passages, the check valve being configured to: (i) open when an oil pressure of the working fluid in the discharge oil passages discharged from the vane pump is higher than the oil pressure in the backpressure oil passages, and (ii) block a flow of the working fluid when the oil pressure of the working fluid in the discharge oil passages discharged from the vane pump is equal to or lower than the oil pressure in the backpressure oil passages.
 2. A vehicle hydraulic device comprising: a vane pump that is driven to rotate by an engine, the vane pump including a pump housing, a plurality of vanes, a rotor, and check valves, the pump housing having an inner peripheral cam surface with an elliptical sectional shape, the plurality of vanes being provided inside the pump housing, the rotor providing vane housing grooves that house the plurality of vanes so as to be movable in a radial direction of the rotor, the check valves being configured to open to allow a flow of a working fluid and close to shut off the flow of the working fluid; and an oil pressure control circuit including backpressure oil passages and discharge oil passages, the backpressure oil passages being configured to supply a backpressure to the plurality of vanes inside the vane housing grooves, the discharge oil passages being configured to: (i) introduce the working fluid discharged from the vane pump, and (ii) supply the working fluid to a device other than the vehicle hydraulic device, wherein the check valves are interposed between the backpressure oil passages and the discharge oil passages, and the check valves are configured to: (i) open when an oil pressure of the working fluid in the discharge oil passages discharged from the vane pump is higher than the oil pressure in the backpressure oil passages, and (ii) block the flow of the working fluid when the oil pressure of the working fluid in the discharge oil passages discharged from the vane pump is equal to or lower than the oil pressure in the backpressure oil passages. 